Attachment for a fuel tank of a fuel cell powered system and electronic portable device equipped therewith

ABSTRACT

An attachment for a fuel tank of a fuel cell powered system is described. The attachment thermally conducts heat generated from an electronic component to the fuel tank. The attachment further affixes to the electronic component by a securing portion. In one aspect, the attachment is comprised in a fuel cell powered electronic device. In another aspect, the attachment is integral to the fuel tank.

FIELD OF THE INVENTION

This relates generally to the field of fuel cells and, morespecifically, to an attachment for a fuel tank of a fuel cell poweredsystem, and to an electronic portable device equipped with such anattachment and fuel tank.

BACKGROUND

Fuel cells have received a great deal of attention in recent years fortheir potential as electricity generators having a relatively lowenvironmental impact. The basic principles of fuel cells have beenunderstood for a long time, but they have had very little widespread usedue to their comparatively high cost of production and the difficulty inmanaging their operation. In addition, while energy generation by a fuelcell typically produces very little in the way of chemical pollution,this benefit is often negated by the energy needed to produce andpackage the fuel for the fuel cell.

Different types of fuel cells also tend to have different operatingparameters that can limit the effectiveness of a particular type forparticular applications. For example, certain fuel cells operate atextremely high temperatures, while others require a compressed gas as afuel source. These different requirements can create safety issues orlimit the power capacity, longevity or other substantive characteristicsof a fuel cell which, in turn, limits its utility for certainapplications.

Despite the limitations of certain types of fuel cells, they remain apromising technology, particularly for certain power applications. Thebasic structure of a fuel cell is known in the art, and will not bediscussed herein. However, an exemplary arrangement is shown in FIG. 1,in which a fuel cell 100 is depicted schematically as providingelectrical power to an electric load 104, which is representative of anelectrical system deriving power from the fuel cell 100. For electricitygeneration, the fuel cell must maintain a reaction that requires asource of an appropriate fuel, e.g., hydrogen (H₂). In FIG. 1, thissource is represented as fuel tank 102, which has a fluid connection tothe fuel cell 100. Depending on the type of fuel cell and fuel beingused, different operating conditions must also be kept within apredetermined range. The operating temperature of the fuel cell, forexample, is different from one type of fuel cell to another. Inaddition, the temperature of the fuel tank must be appropriate for thetype of fuel being used, so as to ensure a proper flow of fuel into thefuel cell.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of an arrangement of a fuel cell adapted toprovide electrical power to an electrical load and a fuel tankdelivering fuel to the fuel cell.

FIG. 2 is a schematic perspective view of a PCB (printed circuit board)such as those used in electronic devices.

FIG. 3 is a schematic side view of a PCB within an electronic device anda fuel cell fuel tank in thermal conduction therewith.

FIG. 4 is a schematic side view of a portion of a PCB with an attachmentfor a fuel tank, the attachment having a securing portion that isadapted to affix the attachment to an edge of the PCB.

FIG. 5A is a schematic side view of a PCB for a device with anattachment for a fuel tank, the attachment having a securing portionthat is adapted to affix the attachment to the PCB and reside in anaperture in the PCB.

FIG. 5B is a schematic top view of a PCB like that of FIG. 5A showingseveral apertures defined in the PCB for affixing an attachment adaptedto be in thermal contact with an electrical component of the PCB.

FIG. 6A is a schematic perspective view of a PCB and a first and secondsurface of the attachment that is integral with the PCB.

FIG. 6B is a schematic perspective view of the PCB of FIG. 6A showing atop portion of the integral fuel tank and attachment system.

FIG. 6C is a schematic perspective view of the PCB of FIGS. 6A and 6Bshowing the integral fuel tank and attachment system integrally adjacentto the PCB.

DETAILED DESCRIPTION

Presented in FIG. 1 is shown an electric load 104 representative of anyof a number of different electrical devices and components. One exampleof such a load is an electrical circuit having at least one electroniccomponent mounted on a printed circuit board (PCB) or embedded in atleast one IC (integrated circuit). The electric load 104 is powered by afuel cell 100 connected to and using fuel stored in fuel tank 102.

FIG. 2 is a schematic representation of a PCB 204 including a number ofdiscrete electronic components. Many electronic components are wellknown for generating a significant amount of heat that must bedissipated to the ambient environment. This may be a particular problemwith small, compact devices that lack the space necessary for efficientheat dissipation.

This disadvantage may be put to good use by thermally conducting heatgenerated by the PCB 204 to, and used by the fuel tank 102. As shown inFIG. 3, the fuel tank 102 is located adjacent to the PCB 204, thusallowing thermal conduction there between. In certain fuel cell systems,the process of generating hydrogen from a fuel source (such as a metalhydride) is an endothermic reaction. In such fuel cells, a reaction isaccomplished when heat is supplied to the fuel in the fuel tank 102. AsPCBs 204 often generate heat, the thermal contact of the PCB 204 to thefuel tank 102 allows use of this heat to increase the temperature of thefuel in the fuel tank 102. For an endothermic reaction, using heatgenerated by adjacent components reduces, or removes completely the needfor heat to be supplied from another source, while simplifying themechanism for dissipating excess heat from the PCB 204.

To ensure appropriate thermal conduction between the PCB 204 and thefuel tank 102, particularly in the case of a portable device 300 whichmay undergo a significant amount of jostling, an attachment 400 is usedbetween the fuel tank 102 and the PCB 204, as shown in FIG. 4. Inaccordance with an aspect, the attachment 400 includes a thermalconductor 414. The thermal conductor 414 has a first surface 410 forthermally contacting directly or ultimately at least one heat-generatingportion of the PCB 204 and a second surface 412 for thermally contactingdirectly or ultimately the fuel tank 102. The thermal conductor 414conducts heat from the first surface 410 to the second surface 412, suchthat heat generated by the PCB 204 is absorbed by the fuel tank 102. Foraffixing the first surface 410 to the PCB 204, the attachment isprovided with a securing portion 406. The second surface 412 ispreferably affixed to the fuel tank 102 by any suitable means, or ispart of the fuel tank 102. The first and second surfaces 410 and 412 ofthe thermal conductor 414 can be in direct contact with respectively theat least one heat-generating portion of the PCB 204 and the fuel tank102. Alternatively, the first and second surfaces 410 and 412 couldfurther covered by a heat conducting material, which could serve as aprotection for the thermal conductor 414.

In accordance with another aspect, the securing portion 406 may furtherinclude a lip 408 located in opposition with the first surface 410 ofthe attachment 400 such that an edge of the PCB 204 resides between thelip 408 and the first surface 410. Between the opposing lip 408 and thefirst surface 410 is a space within which an edge of the PCB 204 may beinserted for securing the attachment thereto. The space between theopposing lip 408 and the first surface 410 is sized so that the PCB 204fits snugly between the first surface 410 and the opposing lip 408,thereby preventing relative movement between the fuel tank 102 and thePCB 204 in a direction perpendicular to the first surface 410 of theattachment 400. The size of the space and the elasticity of the opposinglip 408 may also be such that, when the edge of the PCB 204 resides inthe space, a pressure fit is formed that resists movement of the PCB 204in a direction parallel to the first surface 410. Similar opposing lips408 may also extend from the attachment 400 at other edges of the PCB204. For example, for the PCB 204 having a quadrilateral shape, the lip408 may be used to secure two, three or even all four edges of the PCB204 to thereby further restrict lateral movement of the PCB 204 relativeto the fuel tank 102.

The attachment 400 may also be secured to the PCB 204 in other ways. Inanother aspect shown in FIG. 5A, the attachment 400 is secured to thePCB 204 at one or more anchor points along its surface. An aperture 512,defined by the PCB 204, is indicated by broken lines. The aperture 512provides an anchor point by which the attachment 400 may be attached tothe PCB 204. The attachment 400 has the securing portion 406 thatprojects from the first surface 410 of the attachment 400 and that liesadjacent to the PCB 204. The securing portion 406 is shaped so that anintermediate section 516 fits within the aperture 512 of the PCB 204,and the opposing lip 408 extends in a direction parallel to the firstsurface 410, in opposition to that surface, and contacting a side of thePCB 204 opposite to the side contacted by the first surface 410. Thatis, the attachment 400 holds the fuel tank 102 in thermal contact withthe PCB 204 by being effectively “clipped” to the PCB 204 via thesecuring portion 406 that fits together with the aperture 512. Theintermediate section 516 of the securing portion 406 prevents anyrelative lateral movement between the PCB 204 and the fuel tank 102, andthe lip 408 together with the first surface 410, prevents any relativemovement of the PCB 204 and fuel tank 102 in the perpendiculardirection. It will be understood by a person skilled in the art that itis possible for the attachment 400 to be also affixed to any other partof the device 300 such as to any electronic component or to a casing.

The single attachment 400 may have multiple securing portions 406 andthereby attach to multiple anchor points on the PCB 204. For example, asshown in FIG. 5B, a top view of the PCB 204 indicates two apertures 512within each of which may reside the securing portion 406 of theattachment 400. Having multiple anchor points helps to prevent anyrelative rotational movement of the fuel tank 102 and PCB 204, as wellas translational movement in the three Cartesian directions. In thisexample, two integrated circuits (ICs) 522, 524 are shown mounted to thePCB 204 (other components may also be included, but are not shown in thefigure for simplicity purposes). When the attachment 400 is mounted tothe PCB 204 via the securing portions 406 that fit in the apertures 512,the fuel tank 102 resides in close thermal conduction with both ICs 522,524 and thereby functions as a heat sink for both. A thermallyconductive material 526 may also be located on the PCB 204 in contactwith a component such as IC 522, providing extended thermal surfacecontact between the heat source (the IC) and the fuel tank 102. Such amaterial could be used to increase the effectiveness of the “heat sink”function of the fuel tank 102 by increasing the thermal conduction pathsbetween the IC 522 and the fuel tank 102.

Back to FIG. 5A, according to another aspect, the attachment 400 is anintegral part of the fuel tank's 102 structure. The first surface 410 ofthe attachment 400 has a flat profile and a shape that closely matchesthat of the PCB 204 so as to provide a high degree of heat transferbetween the PCB 204 and the fuel tank 102. The first surface 410 andsecond surface 412 are in thermal conduction to allow the transfer ofheat between the PCB 204 and the fuel tank 102. An interior space 520 ofthe fuel tank 102 in which the fuel is stored may further extend to thesecuring portion 406. This design provides additional fuel storagespace, as well as additional surface area via which heat may be absorbedby the fuel tank 102. Those skilled in the art will recognize that theinterior space 520 may also be limited to the flat region of the fueltank 102.

According to yet another aspect, the attachment 400 has a shape thatcorresponds to the shape of the heat generating PCB 204 and physicallyconforms to the shape of the electronic components or ICs (522,524) ofthe PCB 204. As most PCBs 204 tend to be much larger in length and widththan in thickness (i.e., they tend to have a flat profile), thermalconduction can be enhanced if the first surface 410 of the attachment400 has a shape that corresponds to the shape of the PCB 204. For doingso, the first surface 410 is designed in such a way that its profilematches a surface of the PCB 204.

Reference is now made to FIGS. 6A-6C, which depict yet another aspect.In this particular aspect, the PCB 204, the attachment 400, and the fueltank 102 form a single integrated unit 640. The first surface 410 of theattachment 400 (shown separated from PCB 204 for clarity) is affixedwith the securing portion 406 to a heat-generating portion of the PCB204 in the orientation shown as part of an assembly process. Thesecuring portion 406 is a fastening layer such as a seal applied on thefirst surface 410, however other types of affixing means are alsoapplicable such as the securing portion 406 which is adapted to residewithin the aperture 512 of the PCB 204, the lip 408 which extends in adirection parallel to the first surface 410 or any other effectiveaffixing means. When assembled, this first surface 410 serves as athermal PCB contacting surface. The first surface 410 may be made of oneor many different materials. There are also different means by which toseal the first surface 410 to the PCB 204.

The second surface 412 of the attachment 400 is part of the fuel tank102 to create a fully enclosed interior space 520 (with the exception ofone or more filling/output ports, which are not shown in the figure).Once the integrated unit 640 is assembled, the first surface 410 and thesecond surface 412 isolate the PCB 204 components from the fuel on theinterior space 520 of the fuel tank 102. The fuel tank 102 may bedesigned in any desired shape and volume providing an interior space 520within which the fuel may be stored.

The first surface 410 may be made of heat conducting deformablematerial, which can be applied to the PCB 204 as a conformal coating bya variety of different techniques. A top portion 518, which functions asthe top and sides of the fuel tank 102, may be made of a material withsufficient rigidity at operating temperatures that it retains thedesired shape of the fuel tank 102. FIG. 6C depicts an example of suchan integrated unit 640 once it has been assembled on the PCB 204. Thoseskilled in the art will recognize that, while the heat-generatingportion of the PCB 204 is visible through the integrated attachment andfuel tank system shown in FIGS. 6A-6C, this particularity is used forgraphical representation purposes only, and that it is not necessary forthe integrated unit to be made of transparent material.

A further aspect relates to an electronic portable device including afuel cell powered system and an attachment as previously described. Heatgeneration in an electronic portable device is of particular concern,and use of the heat generated by electronic components to improveperformances of a fuel powered system can be an asset. For doing so, theelectronic portable device includes a fuel tank for storing fuel to beused by a fuel cell for electrical power generation. As previouslydescribed, the thermal conduction between the fuel tank and one orseveral heat generating electronic components is increased by use of theattachment. Any of the previously described aspects of the attachmentcan be used.

The foregoing aspects of the attachment are provided for exemplarypurposes only. Those skilled in the art will recognize that variouschanges in form, material used and design may be made thereto withoutdeparting from the spirit and scope of the attachment, fuel tank andfuel cell powered electronic device as defined by the appended claims.

1. An attachment for a fuel tank of a fuel cell powered system, theattachment comprising: a thermal conductor having a first surface forthermally contacting to at least one heat generating electroniccomponent and a second surface for thermally contacting the fuel tank,the thermal conductor conducting heat generated by the at least oneelectronic component such that heat generated by the at least oneelectronic component is absorbed by the fuel tank; and a securingportion for affixing the first surface to the at least one electroniccomponent.
 2. The attachment of claim 1 wherein the securing portioncomprises a lip located in opposition with the first surface such thatan edge of the at least one electronic component resides between the lipand the first surface and is retained therein.
 3. The attachment ofclaim 2 wherein the securing portion is adapted to reside within anaperture defined by the at least one electronic component.
 4. Theattachment of claim 1 wherein the securing portion is an integral partof the fuel tank.
 5. The attachment of claim 4 wherein the first surfacephysically conforms to the at least one electronic component.
 6. Theattachment of claim 5 wherein the fuel tank is integral with theattachment and defines an interior space for storing fuel.
 7. A fuelcell powered electronic device comprising: a fuel tank adapted to storefuel for delivery to a fuel cell; and an attachment adapted to affix thefuel tank in thermal conduction with at least one heat generatingelectronic component.
 8. The device of claim 7 wherein the attachmentcomprises a securing portion adapted for securely affixing theattachment to the at least one electronic component.
 9. The device ofclaim 8 wherein the securing portion comprises a lip located inopposition with a first surface of the attachment such that an edge ofthe at least one electronic component resides between the lip and thefirst surface and is retained therein.
 10. The device of claim 8 whereinthe securing portion is adapted to reside within an aperture defined bythe at least one electronic component.
 11. The device of claim 7 whereinthe attachment is an integral part of the fuel tank.
 12. The device ofclaim 11 wherein the attachment comprises a first surface thatphysically conforms to the at least one electronic component.
 13. Thedevice of claim 11 wherein the fuel tank defines an interior space forstoring fuel.
 14. A fuel tank and fuel cell powered electronic systemcomprising: at least one heat generating electronic component; a fueltank adapted to store fuel for delivery to a fuel cell; and anattachment adapted to affix the fuel tank in thermal conduction with theat least one heat generating electronic component.
 15. The system ofclaim 14 wherein the attachment comprises a securing portion adapted forsecurely affixing the attachment to the at least one electroniccomponent.
 16. The system of claim 15 wherein the securing portioncomprises a lip located in opposition with a first surface of theattachment such that an edge of the at least one electronic componentresides between the lip and the first surface and is retained therein.17. The system of claim 15 wherein the securing portion is adapted toreside within an aperture defined by the at least one electroniccomponent.
 18. The system of claim 14 wherein the attachment is anintegral part of the fuel tank.
 19. The system of claim 18 wherein theattachment comprises a first surface that physically conforms to the atleast one electronic component.
 20. The system of claim 18 wherein thefuel tank defines an interior space for storing fuel.